The present invention relates to a thrust bearing for compressed air shock absorbers and a compressed air shock absorber.
Suspension struts are used in vehicles for cushioning in uneven terrain and dampening the oscillation and/or vibrations caused by uneven terrain. With the suspension struts, the damping rod extends through the air spring compartment of the air spring bellows, and the pneumatic air space is limited and sealed by means of a damper-head bearing or damper-head seal. The connection of the suspension strut to the vehicle body takes place via the damper-head bearing.
The function of the damper-head bearing is to seal the air spring compartment hermetically, specifically in the area where the piston rod passes through the spring head flange, while simultaneously absorbing axial and radial forces from the damping rod and conducting it to the vehicle body via the damper head mounting. Here elastomer components are used in the damper head mounting.
The sealing function can be integrated into the into the damper head mounting, i.e. the damping rod bracing and the seal may be realized in one single piece. With this concept, however, the required design strongly influences the bearing characteristics due to the air pressure existing in the suspension strut, deviating strongly due to the driving conditions, which is not advantageous.
In the alternative, the sealing function may be realized primarily by a thrust bearing in front or behind the actual support bearing (axial bearing); however, due to the high air pressure to be sealed (up to more than 20 bar) they show a high radial stiffness. Due to the high radial stiffness of the thrust bearing, the arrangement of the thrust bearing in the system can create transverse forces onto the rod of the shock absorber with gimballed stresses. Thus, not only are the dampening characteristics of the absorber negatively influenced but also its endurance characteristics will be reduced.